Modelling Geothermal Resource Utilization by Incorporating Resource Dynamics, Capacity Expansion, and Development Costs

Abstract

can take a long time. While the dynamics of geothermal resources have been considered for individual reservoirs, they have not been studied at a systems level. To study the potential contribution of geothermal resources to sustainable energy system development, it is important to consider the dynamic behavior of resources. Hence, the aim of the paper is to present a System Dynamics model for geothermal power plant expansion considering the dynamics of geothermal resources. The presented model consists of three main modules: resource dynamics, plant construction, and geothermal economics. The geothermal field stock decreases due to utilization for electricity production and increases through natural recharging. Changes in geothermal reservoir stock, and thus in well production capacity, lead to additional well requirement to maintain electricity production levels. Well production capacity not only influences the well construction rate but also influences the unit cost of electricity. Connecting resource dynamics, plant construction and economic aspects on a system’s level, enables the analysis of geothermal resource dynamics in the context of energy system modelling. To showcase the presented model structure, it is applied to Iceland’s geothermal resources available for electricity production but not Iceland’s energy system as a whole. Two main scenarios are simulated and compared based on whether the geothermal resource dynamics are incorporated or not. The simulation results show the implications of incorporating resource dynamics for well construction, generation capacity, and geothermal development cost in long-run. The findings indicate that incorporating the dynamics of geothermal resources into energy system modelling has significant impact on estimated costs. In the cases of incorporated resource dynamics, additional wells are drilled to maintain production levels. This leads to increased total geothermal development cost as well as unit cost. Additionally, when the effects of resource dynamics are incorporated the distribution of resource utilization among different fields is improved, leading to less capacity drawdowns in individual plant areas.